Bicyclus ottossoni Brattström, 2015

Brattström, Oskar, Aduse-Poku, Kwaku, Collins, Steve C. & Brakefield, Paul M., 2015, Revision of the Bicyclus ignobilis species-group (Lepidoptera: Nymphalidae: Satyrinae) with descriptions of two new species, Zootaxa 4018 (1), pp. 57-79 : 71-72

Bicyclus ottossoni Brattström , sp. nov.

( Figs. 19–22 , 29 , 34 )

Type material. Holotype: ♂: Nigeria, Edo State, Ologbo Forest (06°01'N, 05°33'E), 1.iv.2009, O. Brattström leg., OB– IND –1072 ( OBRES). Paratypes: Same location as holotype: 1 ♂: 2.iv.2009, O. Brattström leg., OB– IND – 1077 ( OBRES). 1 ♀: 30.x.2008, O. Brattström leg., OB– IND –0025 ( OBRES). 2 ♀: 10.iv.2010, O. Brattström leg., OB– CAM –0108 & OB– IND –1432 ( OBRES). 1 ♀: 16.xi.2010, O. Brattström leg., OB– CAM –0109 ( OBRES). 1 ♀: 22.xi.2010, O. Brattström leg., OB– IND –1752 ( OBRES). Cameroon: Dja (3°09’N, 13°00’E): 1 ♀, v.2014, OB– ABRI –1015 ( ABRI). Djeng nr. Nfoud (3°25’N, 12°23’E): 2 ♀, xi.2014, OB– ABRI –1060 & OB– ABRI –1061 ( ABRI). Ebogo (3°23’N, 11°28’E): 1 ♂, 2000, OB– ABRI –0026 ( ABRI). 1 ♂, v.2000, ABRI –14–664 ( ABRI). 1 ♂, xi.2001, ABRI –14–663 ( ABRI). Kiosi, S. Cameroon, Eq. Guinea Border (Exact location not identified): 1 ♀, xi.2013, OB– ABRI –1014 ( ABRI). Londji (2°57’N, 09°57’E): 1 ♀, i.1988, OB– ABRI –1013 ( ABRI). Maan (2°22’N, 10°37’E): 1♂, xi.2002, OB– ABRI –0023 ( ABRI). 1 ♂, xi.2004, OB– ABRI –0077 ( ABRI). Mt. Mille (3°17’N, 10°50’E): 1♂, v.2011, OB– ABRI –0087 ( ABRI).

Male description. Forewing length 19–22mm (Holotype 20 mm). The ground colour of the dorsal surface is a uniformly dark brown with a warm hue ( Fig. 19 ). The forewing has a well-developed apical eyespot with an orange outer ring and a white central spot. There is an off-white shading of the apical area of the wing in a basal and anterior direction from the eyespot, but it only forms a well-defined patch in a small area of space 3 below the eyespot. The hindwing has a shiny white costal area extending to the outer margin in space 6, but with some darker scales mixed in close to the margin at the apex. The dorsal forewing has a well defined androconial brush placed basally in space 1b just above vein 1. The brush is about 4mm long, and the hairs are of the same colour as the wing, and aligned along vein 1 pointing towards the margin ( Fig. 22 ). The hindwing has a hair brush originating from close to the base of the cell, the brush is light beige at the base and gradually fades into a pale white yellow at the tip. It covers a patch of light yellow androconial scales located in a small pit where the base of vein 7 originates from the discocellular vein. Vein 1b is slightly enlarged at the middle of its length, with a small collection of hairs located at the base of spaces 1b and 1c covering the basal part of the enlarged section of the vein. There is a concentration of shiny dark short hairs in space 1c extending from the base to about two thirds of the length of the space, and a similar covering of hairs at the base of space 2 and the lower part of the discocellular area. In worn specimens these hairs are often missing, or appear to be arranged in small patches.

The ventral surface base colour is a similar dark warm brown with two beige-purple bands extending across both wings so that a discal band of the ground colour is formed between them ( Fig. 19 ). On the forewing there is an additional light band placed basally in the wing cell angled slightly towards the apex. The basal edge of the main inner light band, and the distal marginal edge of the outer band, gradually fade into the ground colour. The bands are fairly straight across both wings, but with a somewhat wavy outline. At the end of the cell of each wing the light outer band encroaches slightly into the cellular space. All eyespots on the ventral side are surrounded by a light halo of a similar colour to the light bands. This halo turns almost white immediately under the forewing apical patch. The ventral forewing has two well-developed eyespots with yellow-orange outer rings. The hindwing has a row of eight similar eyespots from space 1b up to space 6 (there are two spots in space 1c). All ventral eyespots have white central spots. The eyespot in space 2 is always the largest and the spot in space 3 is variable in size, but usually well developed, especially in specimens from Nigeria. The line of spots follows the outer margin except in spaces 2 and 3 where the spots are shifted inwards. The outer margin of the forewing is less convex than in similar species.

Female description: Forewing length 22–24 mm. The ground colour is variable between specimens, but in general it is of a somewhat warm chocolate brown hue with a well-marked off-white apical patch on the dorsal forewing ( Fig. 20 ). This patch is small for the group, but its margin is unusually well defined, almost appearing like two joined rectangles. The inner angle at vein 4 is especially sharp, with minimal dark colouration along the vein breaking up the band ( Fig. 34 ). There is a well-developed apical eyespot with an orange-yellow outer ring and a white central spot. The apical patch is separated from the patch by a thin dark margin that neatly follows the shape of the eyespot. There is sometimes a small spot below the apical spot, but this is of no diagnostic value and occurs occasionally in all species in the group. There is a minute white spot on the dorsal forewing in space 2 marking the centre of the eyespot that is fully developed immediately beneath on the ventral side. This is not normally seen in females of the other species. The dorsal hindwing is unmarked apart from a slightly lighter costal area. The ventral pattern is vaguely seen through to the dorsal surface. The ventral side is typical for the group and similar to the male, except being a bit lighter and with a more uneven discal band on the distal edge of the hindwing. The lighter areas immediately outside the band enters the wing cells in the distal edge on both fore- and hindwings. Just as in the male, the other margin of the forewing is less convex than in similar species.

Diagnosis. Males of B. ottossoni differ from all other members of the ignobilis -group by the combination of a clear hair brush in space 1b of the forewing together with a minute apical patch on the forewing ( Fig. 19 ). The females are harder to separate from similar species, but the clearly defined apical patch and more squared forewing shape are diagnostic ( Fig. 20 ). The species is verified as a separate unit by the molecular phylogeny. Further details regarding accurate identification of female specimens from the ignobilis -group is found below.

Distribution. The species has a surprisingly discontinuous distribution with a single known Nigerian location in the western Niger Delta (Ologbo), combined with records from a handful of locations in southern Cameroon (all south of Sanaga River) ( Fig. 29 ). The habitat in Cameroon is unknown, but the Nigerian specimens were all collected in a wet swampy rainforest at the edge of the Niger Delta. They were all spotted in shady areas of the forest flying close to the ground. It is likely that the species is present in many more Nigerian sites, but there is limited historic material available and the area is under-surveyed. Without better evidence of true absence from the Eastern Nigerian and Western Cameroonian coastal areas we see no reason at this point to split the populations into subspecies, even if there are small morphological differences, mainly with regards to the eyespot in space 3 on the ventral hindwing being larger in Nigerian specimens.

Etymology. The species is named in honour of Ulf Ottosson. Without his encouragement, generosity and enthusiasm for African fieldwork it is unlikely the first author would ever have set his foot in Nigeria and later embarked on his current research.

Comments. The holotype and some Nigerian paratypes were caught in 2009 during fieldwork for a study of sex pheromones in Bicyclus ( Bacquet, Brattström et al. 2015) . Due to the way sampling for this project was carried out they have had their wings removed from the thorax and one side of the wings has been dissected and used for pheromone analyses. The remaining parts of each specimen are now stored as forewing and hindwing from the one side kept in an envelope, while the bodies are kept separately in vials containing 99% ethanol. All individuals with codes beginning with ‘OB-IND-‘have been sampled and stored in this way.

Figures

FIGURES 19 – 22. Bicyclus ottossoni Brattström sp. nov. 19. Male paratype, Cameroon (OB – ABRI – 0077). 20. Female paratype, Cameroon (OB – ABRI – 1013). 21. Male paratype genitalia, Cameroon (OB – ABRI – 0077). 22. Androconial structures (OB – ABRI – 0077). There is a well-defined brush (encircled in white) in the basal area of space 1 b on the dorsal forewing (also present in B. vandeweghei sp. nov.). The anal area is partly covered by dense dark brown to black hairs and vein 1 b is slightly enlarged from close to its base up to about half of its length. Only the basal part of the hindwing cell-brush is visible as it is mainly covered by the forewing.

FIGURES 27 – 29. Distribution maps for the Bicyclus ignobilis species-group. Records of different species from the same site have been slightly offset when presented in the same map so that all species symbols can be clearly seen. Multiple records close to each other have been collapsed to a single point. The complete distributional data is available in Supplementary Table 1. 27 – 28. B. ignobilis (Open Squares) and B. maesseni (Open Crosses). 27. West Africa up to the Cameroonian border. 28. Cameroonian border and eastwards. 29. Remaining species occurring between Nigeria and Eastern DRC: B. brakefieldi (Filled Circles). B. ottossoni (Filled Crosses). B. rileyi (Open Circles). B. vandeweghei (Filled Diamonds).

FIGURES 30 – 36. Identification of females from the ignobilis- group. The images are not shown to scale, arrows indicate the main characters of importance for identification. 30. B. rileyi is much larger than any other species and the light markings in the apical patch continue below the eyespot in space 2, and often reach the lower margin of the wing. 31. B. maesseni has the edge of the apical patch more broken up in the area closest to the apical eyespot. Also, vein 4 is heavily marked with darker scales, breaking up the patch along its entire length. 32. B. ignobilis (western part of range) almost always lack the ventral hindwing spot in space 3, the apical patch is also much more solid than in B. maesseni with vein 4 just making a dark indentation in the basal part of the light patch. 33. B. ignobilis (eastern part of range) has vein 4 more heavily darkened so that the apical patch is sometimes fully broken up in sections. This makes them appear similar to B. maesseni, but the latter species is not sympatric in the eastern part of the range of B. ignobilis. The ventral discal band gradually gets a more pronounced edge at the end of the cell on both wings in a clinal fashion towards the east of the species range. 34. In B. ottossoni the basal part of the apical patch lacks indentations of dark scales along vein 4. The outer borders of the patch are much better defined than in the other species. The distal margin of the forewing is also much less convex, giving the wing a more squared shape. 35. B. vandeweghei have much more prominent light shading around the hindwing eyespots. The apical patch is otherwise similar to B. ignobilis. 36. B. brakefieldi have a more yellowish colour in the apical patch, and the part of the patch being placed basally of the eyespot is a bit fainter than in other species.